This thesis work has as its ultimate purpose the design of an innovative test bench for a twin-engine piston aircraft for aeronautical use, aimed at certifying the same in compliance with EASA regulations. In addition to the tests required to obtain the certificate of airworthiness, targeted analyzes were planned for the assessment of the stresses discharged from the engine to the helicopter frame in the presence of the failure of one of the two units making up the twin engine. Given the inability to manage all the necessary tests on a single test bench, it was decided to implement two solutions, a bench called static, used for starting and calibrating the engine and a bench called dynamic necessary for checking the transmission, pulleys and moving components as the torque supplied by the engine varies. The two solutions were structurally verified through analytical and numerical analyzes and best set up for housing the twin-engine. Antivibration supports, ring nuts, elastic rings, bearings, free wheels and belts have been suitably sized and integrated into the structures of the two benches. A peculiar small frame, made of folded and welded titanium alloy tubes, has been sized to connect the engine to the frames of the two structures in the best possible way. Analyzes aimed at simplifying the manufacturing and assembly procedures have been defined for both in benches. An innovative air-oil cooling system was therefore designed from scratch for the correct operation of the twin-engine. System consisting of a centrifugal fan with opposed impellers combining volutes and fins in carbon fiber with aluminum impellers. Each of the two test benches was then properly sensorized by choosing the measurement chain and transducers suitable for acquiring dynamic measurements of torque, load on the supports, accelerations, temperature and pressure in the combustion chamber. The analytical formulations and design strategies adopted for the choice and / or design of all the components housed on the two test benches appear within the document.
Il presente lavoro di tesi ha come scopo ultimo la progettazione di un innovativo banco prova per un bimotore a pistoni ad uso aeronautico, finalizzato alla certificazione dello stesso in conformità alle normative EASA. In aggiunta ai test richiesti per l’ottenimento del certificato di aeronavigabilità analisi mirate sono state predisposte per la valutazione delle sollecitazioni scaricate dal motore al telaio in presenza del cedimento di una delle due unità componenti il bimotore. Data l'incapacità di poter gestire tutti i test necessari su un unico banco di prova si è deciso di implementare due soluzioni, un banco denominato statico, utilizzato per la messa in moto e calibrazione del motore ed un banco denominato dinamico necessario per la verifica della trasmissione, delle pulegge e dei componenti in movimento al variare della coppia fornita dal motore. Le due soluzioni sono state verifichiate strutturalmente attraverso analisi analitiche e numeriche ed allestite al meglio per l’alloggiamento del bimotore. Supporti antivibranti, ghiere, anelli elastici, cuscinetti, ruote libere e cinghie sono state opportunamente dimensionate ed integrate nelle strutture dei due banchi. Un peculiare castelletto, realizzato in tubi piegati e saldati in lega di titanio, è stato dimensionato per collegare al meglio motore ai telai delle due strutture. Analisi rivolte alla semplificazione delle procedure di realizzazione ed assemblaggio sono state definite per entrambi in banchi. Un innovativo sistema di raffreddamento aria-olio è stato quindi progettato ex-novo per il corretto funzionamento del bimotore. Sistema composto da un ventilatore centrifugo a giranti contrapposte combinante volute ed alette in fibra di carbonio a giranti in alluminio. Ognuno dei due banchi prova è stato quindi sensorizzato a dovere scegliendo la catena di misura ed i trasduttori adeguati ad acquisire misure dinamiche di coppia, carico sui supporti, accelerazioni, temperatura e pressione in camera di combustione. All' interno di tele documento compaiono le formulazioni analitiche e le strategie di progetto adottate per la scelta e/o la progettazione di tutti i componenti ospitati sui due banchi prova.
Design of a new test bench for an innovative twin aeronautical engine
BENEDETTI, MATTEO
2019/2020
Abstract
This thesis work has as its ultimate purpose the design of an innovative test bench for a twin-engine piston aircraft for aeronautical use, aimed at certifying the same in compliance with EASA regulations. In addition to the tests required to obtain the certificate of airworthiness, targeted analyzes were planned for the assessment of the stresses discharged from the engine to the helicopter frame in the presence of the failure of one of the two units making up the twin engine. Given the inability to manage all the necessary tests on a single test bench, it was decided to implement two solutions, a bench called static, used for starting and calibrating the engine and a bench called dynamic necessary for checking the transmission, pulleys and moving components as the torque supplied by the engine varies. The two solutions were structurally verified through analytical and numerical analyzes and best set up for housing the twin-engine. Antivibration supports, ring nuts, elastic rings, bearings, free wheels and belts have been suitably sized and integrated into the structures of the two benches. A peculiar small frame, made of folded and welded titanium alloy tubes, has been sized to connect the engine to the frames of the two structures in the best possible way. Analyzes aimed at simplifying the manufacturing and assembly procedures have been defined for both in benches. An innovative air-oil cooling system was therefore designed from scratch for the correct operation of the twin-engine. System consisting of a centrifugal fan with opposed impellers combining volutes and fins in carbon fiber with aluminum impellers. Each of the two test benches was then properly sensorized by choosing the measurement chain and transducers suitable for acquiring dynamic measurements of torque, load on the supports, accelerations, temperature and pressure in the combustion chamber. The analytical formulations and design strategies adopted for the choice and / or design of all the components housed on the two test benches appear within the document.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/173793